How Does a Plotter Work?

A plotter is a graphics printer that uses a pen or pencil to draw images. Plotters differ from printers in that plotters use continuous lines to create images while printers use a collection of dots. Like printers, plotters are connected to computers and are used to produce complex images and text. However, plotters are much slower than printers because of the mechanical motion necessary to draw detailed graphics using continuous lines. Architects and product designers use plotters for technical drawings and computer-aided design purposes since plotters have the ability to create large images on oversized sheets of paper. Additionally, many garment and sign manufacturers use cutting plotters in which the plotter's pen is replaced with a sharp razorblade.

A plotter works closely with a computer's imaging software to produce a final picture or object. The first step in using a plotter is to enter the appropriate coordinates for where you want the image to appear on the paper. Modern software allows the user to accomplish this goal very easily by drawing lines and images with the imaging software. Once the schematics for the image are complete, the computer downloads the coordinates to the plotter, which interprets the code and calculates the most efficient path for the pen and paper. Newer plotters use one of two programming languages: Hewlett-Packard's HPGL2 or Houston Instruments' DMPL. Early plotters contained two separate pens, one that moved vertically and one that moved horizontally. These plotters were limited in terms of the complexity of the images they could produce as well as the speed at which they could operate. Modern plotters use a sliding roller, which moves the paper against a stationary pen. A plotter pen is usually a hollow fiber rod with a sharpened end. The ink supply runs through the center of the rod and dispenses through the sharpened tip. The paper moves horizontally and vertically against the pen until the drawing is complete.

Some manufacturers create cutting plotters by replacing a plotter's pen with a knife. The cutting plotter may also contain a pressure control device that regulates how firmly the knife presses down on the material. Many cutting plotters operate by moving the cutter's knife rather than the material itself. However, vinyl sign cutters and other cutting plotters that work with flexible material continue to use the sliding roller featured in pen plotters. Manufacturers who wanted cutting plotters used to purchase and overhaul pen plotters, but many companies have begun producing cutting plotters that can be purchased directly. Cutting plotters are useful in manufacturing a wide variety of items, including customized signs, billboards, posters and vinyl sheets.